I was wondering if it might be simple, or even trivial, for a hardware Midi controller that features "MPE Midi" (e.g. roli seaboard rise, eigenharp, and so on) to work as a Midi controller via the bomebox? The roli seaboard rise is described as "class compliant" but was wondering whether this special implementation of Midi might have some idiosyncrasies that would make the problem more difficult? I am aware that this MPE (note-per-channel) method would likely require some mapping/manipulation, but theoretically, if the user is capable enough, do you expect it would work?

First of all, MPE is just plain MIDI, so you can directly use it with any other MIDI device/synth/DAW/... MPE devices certainly work fine with the BomeBox!

But, because MPE uses multiple MIDI channels for one keyboard/player, some things won't work as expected with non-MPE gear. For that, you can use a MIDI Translator Pro project to somewhat convert MPE to a single-channel MIDI stream, but you'll loose much of the per note expression, including per-note slides (if other notes are playing, too).

If you can tell us an exact use case, I can tell you in more detail, how/if that's possible.
Thanks,
Florian

Thanks!
That is basically the answer I was hoping for, I understand the note-per-channel limitations and such, and that mapping may help solve certain of these issues for certain use cases, and thanks for the offer of further help. Essentially my use case is that I don't have any of these devices, in part because I previously discarded the idea of owning one, as I understood them to rely on a computer connection and software from a very small list. The Bomebox now re-opens up options for me, and others, when it comes to using these devices with other gear. A fairly simple example might be using a roli seaboard rise to trigger a 4-channel hardware synth module.

indeed! Also note that many synths should work fine with MPE if they support the same patch on all channels. Just some specialties of MPE will not be supported.
You should be able to try with the NOISE app from Roli -- for iOS. I thought it can be used to send MPE.
Thanks,
Florian